The invention relates to an exhaust manifold for an internal combustion engine, having at least one exhaust pipe and a flange which can be fastened to an engine block of the internal combustion engine. On the side facing away from the engine block, the flange is provided with a channel which is connected to a fluid line and which is in fluid communication with the interior of the exhaust pipe via a lateral opening in the exhaust pipe.
It is often desirable to feed secondary air to an exhaust system of the internal combustion engine, for the purpose of which an introduction of fluid into the exhaust pipes of the internal combustion engine is required. Because of the high temperature differences existing between the individual components, especially between the engine block and the exhaust pipes, high technical expenditures are required for creating a tight long-lasting connection.
An above-described exhaust manifold is known, for example, from German Patent document DE 43 15 086 A1. In the case of the exhaust manifold shown in DE 43 15 086 A1, the secondary air is introduced by way of the engine block into the flange and from there into the exhaust pipes. For this purpose, corresponding fluid connections have to be created between the engine block and the flange. This approach requires high technical expenditures and costs.
It is an object of the invention to present a cost-effective alternative for the introduction of fluid into the exhaust system.
In the case of an exhaust manifold of the above-mentioned type, it is provided for this purpose according to the invention that the fluid line leads into the channel on the side of the flange facing away from the engine block. In this manner, connections from the channel to the interior of the engine block will no longer be necessary. With the exception of the lead-through openings of the exhaust pipes, the flange can therefore be constructed to be closed on the engine block side. The introduction of fluid, for example, secondary air, into the channel as well as the introduction of the fluid from the channel into the exhaust pipe or the exhaust pipes takes place on the side of the flange facing away from the engine block.
The channel may be in direct fluid communication with the interior of the exhaust pipes. As an alternative, the fluid may first flow into the air gap of an LSI manifold and then into the exhaust pipes.
In a preferred embodiment of the invention, the channel is formed by a sheet metal component and extends along a flange surface, which is situated opposite the flange surface that rests on the engine block. The sheet metal preferably is a separate second part which is connected with the flange, for example, by welding or the like. Since the flange rests against the engine block, thus, for example, against the cooled cylinder head, the temperature differences occurring there during operation are clearly lower than in the area of the exhaust pipes. For this reason, a connection of the sheet metal component with the flange is subjected to less severe temperature fluctuations and is therefore subject to different, less extensive, thermal expansions. The use of an otherwise customary compensation element between the individual components will therefore not be necessary.
The sheet metal component forming the channel preferably has an essentially U-shaped cross-sectional profile, the legs of the profile pointing to the flange surface. The volume of the channel can be defined in a simple manner by way of the length of the legs and the width of the preferably flat connecting web between the latter, in which case a relatively large volume requiring little space can also be implemented.
The sheet metal component forming the channel preferably has an attachment for the connection to the fluid line, for example, in the form of a molded-on connecting piece.
The channel can be constructed such that all exhaust pipes extending through the flange lead through the channel or, in other words, are at least partially surrounded by the channel. The channel may extend along the entire width of the cylinder head. As a result, each of the exhaust pipes can easily be supplied with the fluid, for example, with secondary air.
The opening in the exhaust pipe is, for example, formed by a lateral slot.
The exhaust pipes may be surrounded by an outer shell of an air gap insulation, which also takes place in the case of a known LSI manifold. However, the invention can also be used in exactly the same manner in the case of exhaust manifolds without any air gap insulation.
When an air gap insulation is used, the sheet metal component forming the channel is preferably arranged within the outer shell.
The exhaust pipe or pipes may extend through the flange.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.